In the field of optical communications, an input optical power is the amount of work done by input light per unit time.
Currently, an optical signal is directly input into a receiver. Because a one-to-one correspondence may exist between an input optical power Y of a received signal and a detection voltage value X of the receiver, a method for determining an input optical power in a traditional optical module is: (1) measuring several input optical powers and corresponding detection voltage values; (2) finding a relational expression between the input optical powers and the voltage values, for example, Y=f(X); and (3) calculating an input optical power value under any voltage value.
As requirements for a transmission distance of an optical signal and a transmission capacity become higher, compared with the traditional optical module, some optical modules currently use an optical amplification technology to amplify optical power of a signal and prolong the transmission distance.
FIG. 1 describes a structural diagram of an optical module that uses the optical amplification technology to amplify optical power of a signal. In FIG. 1, optical signals of multiple wavelengths are combined into one sequence of optical signals, and after being amplified by an optical amplifier, the sequence of optical signals are output to optical receivers, where each optical receiver corresponds to one wavelength, and each optical receiver receives an optical signal of a wavelength corresponding only to the optical receiver itself. Then, a received optical signal is converted into an electrical signal for output.
The optical amplifier amplifies an input optical power of an optical module to some extent, and what is detected by an optical receiver is an amplified optical power. Therefore, the input optical power cannot directly correspond to a detection voltage value of the optical receiver. As a result, the optical module that uses the optical amplification technology cannot use the foregoing method for determining an input optical power in the traditional optical module; and up to now, for the optical module that uses the optical amplification technology, there lacks a method for determining the input optical power.
In conclusion, currently, there is still no solution for determining an input optical power of an optical signal on which optical amplification is performed.